Question

Which of the following are roots of the polynomial function? Check all that apply f(x) = x^3 + 3x^2 - 9x + 5

Answer 1

Answer:

x = 1 or x = -5

Step-by-step explanation:

Solve for x:

x^3 + 3 x^2 - 9 x + 5 = 0

The left hand side factors into a product with two terms:

(x - 1)^2 (x + 5) = 0

Split into two equations:

(x - 1)^2 = 0 or x + 5 = 0

Take the square root of both sides:

x - 1 = 0 or x + 5 = 0

Add 1 to both sides:

x = 1 or x + 5 = 0

Subtract 5 from both sides:

Answer:  x = 1 or x = -5